Russia expelled four British diplomats yesterday and suspended co-operation on counter-terrorism in the latest move in the row over the refusal to extradite a murder suspect.

However, President Vladimir Putin said he believed the "mini-crisis" would be overcome.

"I think relations between Russia and Britain will develop normally because both countries are interested in this," he said.

Mikhail Kamynin, Russia's Foreign Ministry spokesman, said that the four British embassy staff were "persona non grata" and should leave the country within 10 days.

It came three days after Britain announced the expulsion of four diplomats from the Russian embassy in London in response to Russia's refusal to extradite the man charged with killing Alexander Litvinenko.

Britain yesterday called Russia's response "completely unjustified" and said it was disappointed Moscow had not signalled any fresh co-operation over the extradition of Andrei Lugovoy.

The Crown Prosecution Service announced in May that it would seek the extradition of the former KGB bodyguard to face trial for the murder of Litvinenko. However, Moscow has said that its constitution prohibits the extradition of its citizens.

As part of Russia's response, which the Kremlin deputy spokesman called "proportionate", it will also stop issuing visas to British officials.

Gordon Brown's spokesman said the Prime Minster was "disappointed" with the response of the Russians.

He added that they were "examining the implications"

of Russia's statement, including its withdrawal of co-operation on counter-terrorism.

He said: "We seek a constructive and co-operative relationship with Russia across a broad front, including counter-terrorism."